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Wednesday, June 14, 2006

ANIMAL TRACKER

Cattle egret


* Japanese name: Amasagi
* Scientific name: Bubulcus ibis
* Description: Cattle egrets are in the heron family, but they are shorter and have stouter necks than their relatives. They have a "hunched" posture, even when they stand up straight. They are medium-sized birds, 46-56 cm long, with a wingspan of around 90 cm. The legs are dull orange, and the plumage is usually white, except during the breeding season, when the eyes, bill and legs turn red and the feathers on the head, throat and back turn an eye-catching orange color.
* Where to find them: From Honshu to Kyushu and Okinawa. Being wading birds, cattle egrets are found in rice fields and ponds and lakes, but for a heron they are surprisingly well-adapted to terrestrial habitats and can often be seen in urban areas too. Despite the name, they are often, though not always, associated with cattle. Cattle egrets are what biologists call a "cosmopolitan" species -- that's not to say they are sophisticated, just that they live all over the world. Sometimes they nest in large groups in the same tree, where birds will steal nest material when their neighbors aren't watching. It is the national bird of Botswana.
* Food: Mostly insects, often grasshoppers that have been disturbed by cattle. Also amphibians, reptiles and young birds, which they stab with their dagger-like bill. In the nest, chicks will squabble with each other quite strongly over food, and the first-born and largest chick usually wins. Very occasionally sibling fights become so serious that one is killed.
* Special features: Male and female cattle egrets form interesting relationships. Males establish territories, and perform courtship displays to try and win a female. When a watching female makes her choice, she flies over and lands on his back. Sometimes two females make the same choice, so more courtship ensues until only one remains. The pair will stay together for the season until their chicks have fledged. Then they split up and will find another partner for the next season. After he has bonded with his female, the male takes her to another site, where they will set up a nest together. This is also where mating takes place. In contrast to the elaborate courtship, there is no ceremony before mating. Some biologists have reported seeing egrets making "forced" copulations. The male and female will, nonetheless, continue to respectfully greet each other when returning to the nest from a feeding trip, by raising plumes on the back. Females lay 3-4 eggs.

PHOTO COURTESY OF BIO-IMAGE NET



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